From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>,
Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure
Date: Mon, 05 Dec 2016 16:00:54 +0100 [thread overview]
Message-ID: <1480950054.31788.36.camel@sipsolutions.net> (raw)
In-Reply-To: <58458058.5020008@candelatech.com>
On Mon, 2016-12-05 at 06:57 -0800, Ben Greear wrote:
> I think clearing sdata-in-driver would fix the ath10k problem, at
> least, but I was afraid it would break something else in mac80211 or
> maybe in other thick firmware drivers.
It's pretty much an internal thing - not sure what it'd break. OTOH,
some drivers might actually assume that iterating finds them all, if
they never clear the data even across a restart?
> One way or another, we cannot be iterating over interfaces while
> the interfaces are at the same time being (re)added.
Well, we obviously *can* be, and we do in fact do that - it's just that
ath10k specifically has issues with the data it's putting there, no?
> Maybe mac80211 should explicitly remove all interfaces from the
> driver during crash recovery?
I don't think that'll work. Removing them would interact with the
firmware, which is dead, etc. That'd just cause trouble.
> And the behaviour needs to be clearly documented somewhere
> easy to find so that we can think about and program to the correct
> API behaviour.
We assume that the driver resets all its internal state - this whole
interface iteration is a corner case we hadn't considered, I suppose.
johannes
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WARNING: multiple messages have this Message-ID (diff)
From: Johannes Berg <johannes@sipsolutions.net>
To: Ben Greear <greearb@candelatech.com>,
Michal Kazior <michal.kazior@tieto.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure
Date: Mon, 05 Dec 2016 16:00:54 +0100 [thread overview]
Message-ID: <1480950054.31788.36.camel@sipsolutions.net> (raw)
In-Reply-To: <58458058.5020008@candelatech.com>
On Mon, 2016-12-05 at 06:57 -0800, Ben Greear wrote:
> I think clearing sdata-in-driver would fix the ath10k problem, at
> least, but I was afraid it would break something else in mac80211 or
> maybe in other thick firmware drivers.
It's pretty much an internal thing - not sure what it'd break. OTOH,
some drivers might actually assume that iterating finds them all, if
they never clear the data even across a restart?
> One way or another, we cannot be iterating over interfaces while
> the interfaces are at the same time being (re)added.
Well, we obviously *can* be, and we do in fact do that - it's just that
ath10k specifically has issues with the data it's putting there, no?
> Maybe mac80211 should explicitly remove all interfaces from the
> driver during crash recovery?
I don't think that'll work. Removing them would interact with the
firmware, which is dead, etc. That'd just cause trouble.
> And the behaviour needs to be clearly documented somewhere
> easy to find so that we can think about and program to the correct
> API behaviour.
We assume that the driver resets all its internal state - this whole
interface iteration is a corner case we hadn't considered, I suppose.
johannes
next prev parent reply other threads:[~2016-12-05 15:01 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-02 2:29 [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure greearb
2016-12-02 2:29 ` greearb
2016-12-02 2:30 ` [PATCH 2/2] ath10k: work-around for stale txq in ar->txqs greearb
2016-12-02 2:30 ` greearb
2016-12-05 8:13 ` [PATCH 1/2] mac80211: do not iterate active interfaces when in re-configure Michal Kazior
2016-12-05 8:13 ` Michal Kazior
2016-12-05 13:52 ` Johannes Berg
2016-12-05 13:52 ` Johannes Berg
2016-12-05 14:57 ` Ben Greear
2016-12-05 14:57 ` Ben Greear
2016-12-05 15:00 ` Johannes Berg [this message]
2016-12-05 15:00 ` Johannes Berg
2016-12-05 15:06 ` Ben Greear
2016-12-05 15:06 ` Ben Greear
2016-12-05 17:23 ` Adrian Chadd
2016-12-05 17:23 ` Adrian Chadd
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